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'Porphyrins' in keywords Facet   Publication Year 1998  [X]
Facet   section ZfN Section B  [X]
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1Author    Steffen Runge, M. Athias, O. SengeRequires cookie*
 Title    Electron Donor-Acceptor Compounds. Synthesis and Structure of 5-(l,4-Benzoquinone-2-yl)-10,15,20-trialkylporphyrins  
 Abstract    A series of 5-(benzoquinone)-10,15,20-trialkylporphyrins was synthesized via cross conden­ sation of the respective aldehydes, 2,5-dimethoxybenzaldehyde and pyrrole followed by de-methylation with BBr3 and oxidation with P b 0 2. This method worked reasonably well for compounds bearing the benzoquinone substituent and butyl, isopropyl, 1 -methylpropyl and 2-ethylpropyl residues (2a-d). The free base porphyrin quinones were converted into the zinc(II) complexes (3a-d) all of which showed remarkable stability for porphyrin quinones. The zinc(II) complex 3c bearing isopropyl residues was investigated by X-ray crystallography and showed a supramolecular structure consisting of polymeric chains facilitated by coordina­ tion of a benzoquinone oxygen to a neighboring zinc(II) center. Attempts to synthesize a 5-(benzoquinone)-10,15,20-tris(terr-butylporphyrin) resulted in the formation of a yellow por-phomethene (4), which could not be oxidized further. A crystal structure analysis of 4, the first for a free base porphomethene, shows an extremely twisted conformation with syn-orientation of the three rm-butyl groups. The results indicate that new methods will have to be developed for the synthesis of nonplanar porphyrin quinones. 
  Reference    Z. Naturforsch. 53b, 1021—1030 (1998); received June 15 1998 
  Published    1998 
  Keywords    Porphyrins, Quinones, Electron Transfer Compounds, Crystal Structure, Conformation 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-1021.pdf 
 Identifier    ZNB-1998-53b-1021 
 Volume    53